Array of light emitting devices with reduced optical crosstalk

ABSTRACT

An array comprising a plurality of light emitting pixels, wherein at least two of the plurality of light emitting pixels are separated by organic semiconductors dispersed in a medium, wherein the organic semiconductors are configured to absorb light of a predefined wavelength, thereby to reduce optical crosstalk across the medium between the at least two of the plurality of light emitting pixels.

FIELD OF THE INVENTION

The invention relates to arrays of light emitting pixels and methods offorming arrays of light emitting pixels. In particular, but notexclusively, the invention relates to arrays of light emitting diodedevices with reduced optical crosstalk and methods of forming arrays oflight emitting diode devices with reduced optical crosstalk.

BACKGROUND OF THE INVENTION

Light emitting devices are known to have a wide range of practicalapplications, including, for example, in display technologies. Inparticular, it is known that light emitting diode (LED) devices have thepotential to provide efficient sources of light for a wide range ofpixel-array based display technologies. Increases in LED lightgeneration efficiency and extraction, along with the production ofsmaller LEDs (with smaller light emitting surface areas) and theintegration of different wavelength LED emitters into arrays, hasresulted in the provision of high quality colour arrays with multipleapplications. However, as the pixel pitch in such arrays is reduced tovery small pitches (e.g., less than 5 μm) in order to provide higherresolution arrays of micro LED based pixels, a number of difficultiesarise, in particular with respect to the fabrication of such arrays andthe colour gamut.

One particular challenge in reducing the pixel pitch in arrays of microLED devices is the separation of individual light emitting pixels suchthat light emitted by one pixel does not interfere with light emitted byanother pixel in the array. Where there is such crosstalk in lightemission between pixels in an array, the resultant array has a reductionin the overall quality (including colour and contrast) of light that isemitted.

Known techniques, for reducing optical crosstalk between pixels, forexample in liquid crystal display (LCD) applications, do so by using‘black absorbers’ to create a matrix surrounding individual pixels inarrays pixels. However, black absorbers, such as ‘black resist’ (forexample the pigmented photoresist for a black matrix described by Kudoet al, Journal of Photopolymer Science and Technology, Volume 9, Number1 (1996), 121-130) are typically unable to be resolved less than 10 μm,making them unsuitable for very high resolution micro LED arrays, wherethe pixel pitch is less than 5 μm.

Accordingly, since the size of features in high resolution arrays, suchas micro LED arrays, is very small, significant challenges are seen inthe processing of arrays to provide high quality micro LED devices withrelatively low optical crosstalk.

SUMMARY OF THE INVENTION

In order to mitigate for at least some of the above-described problems,there is provided an array of light emitting pixels in accordance withthe appended claims. Further, there is provided a method for forming anarray of light emitting pixels in accordance with the appended claims.

There is provided an array comprising a plurality of light emittingpixels, wherein at least two of the plurality of light emitting pixelsare separated by organic semiconductors dispersed in a medium, whereinthe organic semiconductors are configured to absorb light of apredefined wavelength, thereby to reduce optical crosstalk across themedium between the at least two of the plurality of light emittingpixels. Further, there is provided a method of forming an arraycomprising a plurality of light emitting pixels, wherein at least two ofthe plurality of light emitting pixels are separated by organicsemiconductors dispersed in a medium, wherein the organic semiconductorsare configured to absorb light of a predefined wavelength, thereby toreduce optical crosstalk across the medium between the at least two ofthe plurality of light emitting pixels.

Advantageously, high resolution arrays can be provided with improvedcolour contrast and gamut.

Preferably, at least two of the plurality of light emitting pixels areseparated by a distance of less than or equal to 2 μm and preferablyless than or equal to 1 μm.

Advantageously, very high resolution arrays of light emitting pixels areprovided, enabling improved displays suitable for applications thatbenefit from particularly high resolution arrays, such as augmentedreality applications, where the display is typically formed in closeproximity to a user.

Preferably, at least two of the plurality of light emitting pixels eachcomprise a micro light emitting diode (LED) device (e.g., LED devicesformed on a micro scale, as understood by the skilled person, where thelight emitting surface of the micro LED is of the order of less than orequal to 100 μm² and where the pixel pitch of a micro LED array is lessthan or equal to 10 μm).

Advantageously, micro LED devices are efficient sources of light thatform efficient arrays of light emitting pixels with reduced energyconsumption and increased light output compared with other lightsources.

Preferably, at least one of the plurality of light emitting pixelscomprise a light conversion layer arranged to receive input light with aprimary peak wavelength and convert the input light to output light witha different primary peak wavelength.

Advantageously, light conversion layers enable the use of highlyefficient LEDs, such as blue-emitting nitride based epitaxially growncrystalline semiconductor devices to be used as a pump source forconversion layers, thereby enabling the most efficient LEDs to be usedwhilst reducing the need for different types of LED to be implemented inan array.

Preferably, the organic semiconductors are conjugated organicsemiconductors comprising a plurality of conjugated structures,preferably wherein the organic semiconductors are organicsemiconductors, more preferably wherein the plurality of conjugatedstructures comprise a core and an arm.

Advantageously, such organic semiconductors are tunable to providefunctionality that enables them to be implemented into standardsemiconductor fabrication techniques whilst enabling efficientprocessing of structures with smaller features than in the known art.

Preferably, at least two of the plurality of conjugated structures havea different functional property.

Advantageously, multi-functionality means that organic semiconductorsare implementable in colour conversion layers to provide high quality,fast response down conversion of the wavelength of input light.Beneficially, multi-functionality means that organic semiconductors aretunable to absorb multiple wavelengths of light, thereby to provide anefficient absorbing layer that facilitates shorter pixel pitch in arraysof light emitting pixels.

Preferably, the array comprises further organic semiconductorsconfigured to absorb light of a further predefined wavelength differentto the predefined wavelength.

Advantageously, specific wavelengths of light are absorbed by differentorganic semiconductors, thereby to extend the range of undesirablewavelengths that would otherwise contribute to optical crosstalk betweenlight emitting pixels.

Preferably, the organic semiconductors are configured to absorb light ofa predefined range of wavelengths comprising the predefined wavelength.

Advantageously, ranges of light, such as visible light, are absorbed,thereby aiding a reduction in optical crosstalk between light emittingpixels and providing improved colour emission from the array.

Preferably, the medium is at least one of a resin and a polymer medium.

Advantageously, resins and polymers provide media in which organicsemiconductors are dispersed, whilst enabling efficient processing thatuses known semiconductor fabrication tools in an economical (time andcost) manner

Preferably, the array is a high resolution micro LED array with a pixelpitch less than 10 μm, preferably less than 4 μm.

Advantageously, the use of organic semiconductors in high resolutionarrays of light emitting pixels enables reduced optical crosstalk on ascale that has particularly advantageous applications that benefit fromsuch high resolution.

Preferably, the plurality of light emitting pixels each have a lightemitting surface that is less than or equal to 100 μm², preferably lessthan 16 μm².

Advantageously, not only are closer pixels achievable by reducing thepixel pitch, but smaller light emitting surfaces are producible, therebyenhancing the overall emission from a high resolution array of lightemitting pixels whilst maintaining colour integrity.

Further aspects of the invention will be apparent from the descriptionand the appended claims.

DETAILED DESCRIPTION OF AN EMBODIMENT OF THE INVENTION

A detailed description of embodiments of the invention is described, byway of example only, with reference to the Figures, in which:

FIG. 1A shows a cross sectional view of three light emitting pixels;

FIG. 1B shows a plan view of an array of light emitting pixels;

FIG. 2 shows an absorption spectrum of a material comprising organicsemiconductors; and

FIG. 3 shows light emission spectra through different thickness ofmaterial comprising organic semiconductors.

As described above, down-scaling arrays of light emitting diode (LED)devices to produce high resolution micro LED arrays with associatedmicro-scale light emitting pixels results in difficulties associatedwith optical crosstalk between light emitting pixels in the arrays andhence a diminution in the purity of light associated with light emittingpixels, and in the contrast between light emitting pixels compared witharrays formed from larger features (e.g., with longer pixel pitch and/orconventionally larger LED devices). A structure and method describedwith reference to FIGS. 1A to 3 provides for an array of light emittingpixels with reduced optical crosstalk, enabling the provision of highresolution micro LED arrays with improved colour gamuts and contrast.

FIG. 1A shows a cross-sectional view 100 of three light emitting pixels116 a, 116 b, 116 c. There is shown a complementary metal oxidesemiconductor (CMOS) backplane 102, upon which there is provided anarray of micro LEDs 104 a, 104 b, 104 c. The CMOS backplane 102 isconfigured to work with the micro LEDs 104 a, 104 b, 104 c in orderselectively to control light emission from the array of micro LEDs.There are three micro LEDs 104 a, 104 b, 104 c shown in FIG. 1A. Themicro LEDs 104 a, 104 b, 104 c are nitride based epitaxial crystallinesemiconductor LEDs configured to emit light with a primary peakwavelength that is blue (approximately 450 nm). In order to provide ared-green-blue (RGB) multi-colour display, the blue light emitted by themicro LEDs 104 a, 104 b, 104 c is converted using colour conversionlayers that are formed on the micro LEDs 104 a, 104 b, 104 c.

The view 100 of FIG. 1A shows a first blue micro LED 104 a upon whichthere is deposited a clear resin 112. Upon the clear resin 112 there isdeposited a protective, passivation, layer 114. The protective layer 114is transparent to visible light and forms at least part of a lightemitting surface associated with the micro LED 104 a. The micro LED 104a, the clear resin 112 and the protective layer 114 form a first lightemitting pixel 116 a. Whilst a clear resin 112 is used to processing ofthe protective layer 114 such that the protective layer 114 is uniformlydistributed across different light emitting pixels in an array of lightemitting pixels, in further examples, alternative or additional layersare used instead of clear resin 112. In further examples, the clearresin 112 is omitted where colour conversion of light from an associatedlight emitting diode device is not used.

There is also shown a second blue micro LED 104 b, upon which there isformed a colour conversion layer 108 that is configured to convert lightfrom the micro LED 104 b such that input light with a primary peakwavelength that is blue is converted to a primary wavelength that isred. Upon the colour conversion layer 108 there is a passivation,protective layer 114. The protective layer 114 is transparent to visiblelight and forms at least part of a light emitting surface associatedwith the micro LED 104 b. The micro LED 104 b, the colour conversionlayer 108 and the protective layer 114 form a second light emittingpixel 116 b.

There is also shown a third micro LED 104 c that is configured to emitlight with a primary peak wavelength that is blue (approximately 450nm). Upon the third blue micro LED 104 c, there is provided a colourconversion layer 110 that is different to the colour conversion layer108 associated with the second micro LED 104 b. The second colourconversion layer 110 is configured to receive input light from the thirdmicro LED 104 c and convert it from light that has a primary peakwavelength that is blue light to light that has a primary peakwavelength that is green. Upon the colour conversion layer 110 there isa passivation layer that functions as a protective layer 114. Theprotective layer 114 is transparent to visible light and forms at leastpart of a light emitting surface associated with the micro LED 104 b.The micro LED 104 a, the colour conversion layer 110 and the protectivelayer 114 form a third light emitting pixel 116 c.

The colour conversion layers 108, 110 described with respect to FIG. 1Acomprise a medium in which organic semiconductors are dispersed. It isknown that down converting organic semiconductors can be tuned in orderto achieve targeted physical properties. In particular, advantageously,organic semiconductors can achieve specific values for the ionisationpotential or electronic affinity, absorption and emissioncharacteristics, charged transport properties, phase behaviour,solubility, and processability. Typically, organic semiconductors areconjugated organic semiconductors comprising a plurality of conjugatedstructures. In an example, such conjugated structures include a core andarm. The functionality of these constituent parts of the organicsemiconductor are tuned in order to provide particular characteristics.

Macromolecules are discussed in Acc. Chem. Res 2019, 52, 1665 to 1674and J. Mater. Chem. C, 2016, 4, 11499, for example. Macromolecules thatare tunable include conjugated organic semiconductor comprising aplurality of conjugated structures. These are typically organicsemiconductors. Such structures are formable to comprise a core and anarm. The plurality of conjugated structures can be formed to have adifferent functional properties, for example, different absorptionand/or emission characteristics.

With reference to the colour conversion layers 108, 110, of FIG. 1A, theorganic semiconductors in these layers are configured to absorb bluelight received from their respective LED 104 b, 104 c. The organicsemiconductors are then further configured to emit light at a different,converted wavelength. For example, one light emitting pixel 116 b isconfigured to emit red light from the colour conversion layer 108 uponabsorption of blue light from the micro LED 104 b. Another pixel 116 cis configured to emit green light from the colour conversion layer 110upon absorption of blue light from the micro LED 104 c. Advantageously,the use of organic semiconductors enables thin colour conversion layersto be implemented that facilitate smaller LEDs. Whilst the colourconversion layers 108, 110 described with respect to FIG. 1A arearranged to absorb and emit light of particular wavelengths, the skilledperson understands that in further examples, alternatively oradditionally, different combination and configurations of lightwavelength conversion are used in order to provide different arrays oflight emitting pixels.

The LEDs 104 a, 104 b, 104 c are epitaxially grown as a monolithic arrayof blue micro LEDs with primary light emitting surfaces of less than orequal to 10 μm². In further examples, alternatively or additionally, theLEDs 104 a, 104 b, 104 c are associated with the CMOS backplane 102using pick and place methods, for example. The blue micro LEDs 104 a,104 b, 104 c are nitride-based epitaxially grown compound crystallinesemiconductor LEDs. In further examples, other LEDs are used, such asother group III-V, or group II-VI based materials. In further examples,alternative or additional LEDs of different sizes and shapes areimplemented. Advantageously, the LEDs 104 a, 104 b, 104 c are grownmonolithically, thereby to provide high quality material with excellentuniformity and efficiency, without a requirement to transfer individualLED devices. Beneficially, the monolithic LED array is coupled to abackplane 102 in order to enable control of individual LEDs 104 a, 104b, 104 c in the monolithic array. The LEDs 104 a, 104 b, 104 c are grownas part of a monolithic array of LEDs using metal organic chemicalvapour deposition (MOCVD). In further examples, alternative and/oradditional techniques are used to form the LEDs 104 a, 104 b, 104 c aspart of a monolithic array, such as molecular beam epitaxy (MBE) andother suitable deposition/growth techniques. In further examples, otheradditional and/or alternative semiconductor fabrication and processingtechniques are used to provide the monolithic array of LEDs 104 a, 104b, 104 c.

In-between each of the light emitting pixels 116 a, 116 b, 116 c, formedby the combination of a micro LED with or without colour conversionlayers, there is provided an infill 106. The infill 106 is formed bydispersing organic semiconductors in a medium and patterning ordepositing the medium between light emitting pixels to form a matrix ofinfill 106. As described above with reference to the colour conversionlayers 108, 110, organic semiconductors are tunable to provide certainproperties. The organic semiconductors dispersed to form the infill 106are configured to absorb light of a predefined wavelength. Whilst theinfill 106 is described with respect to a medium in which organicsemiconductors configured to absorb light of a predefined wavelength, infurther examples, the medium comprises further organic semiconductorsconfigured to absorb light at a further predefined wavelength, differentto the predefined wavelength.

In the example of FIG. 1A, the infill 106 is configured to absorbvisible light for a predefined range of wavelengths. Advantageously, theinfill 106 is formed in between light emitting pixels 116 a, 116 b, 116c such that light emitted by the micro LEDs 104 a, 104 b, 104 cassociated with each of the light emitting pixels 116 a, 116 b, 116 c isabsorbed around the periphery of each of the light emitting pixels 116a, 116 b, 116 c surrounded by the infill 106. Advantageously, the infill106 forms a matrix around the light emitting pixels 116 a, 116 b, 116 cthat confines light emission from the light emitting pixels 116 a, 116b, 116 c to a light emitting surface associated with each of the lightemitting pixels. Beneficially, the use of a passivation, protectivelayer 114 buries the light emitting structures (formed from the microLEDs and the colour conversion layers) such that the light emitted byeach light emitting pixel is confined laterally, thereby aiding thecontrast between light emitting pixels and aiding the colour gamut ofthe resultant array of light emitting pixels.

FIG. 1B shows a plan view 100′ of an array of pixels in a micro LEDarray. There is shown a matrix of infill 106 surrounding pixels 116. Thepixels 116 correspond to any of the combinations of micro LED 104 a, 104b, 104 c with colour conversion layers 108, 110 or clear resin 112described with respect to FIG. 1A and in FIG. 1B there is shown blue,green and red light emitting pixels 116 a, 116 b, 116 c described withrespect to FIG. 1A amongst other light emitting pixels 116. Whilst thelight emitting pixels 116 a, 116 b, 116 c of FIG. 1A and FIG. 1B areshown in a particular arrangement, in further examples, arrays of lightemitting pixels comprise any appropriate number of light emitting pixelsin any suitable arrangement and with any suitable light emitting surfaceassociated with each of the light emitting pixels. Whilst the infill 106is shown to surround each individual pixel, in further examples theinfill 106 alternatively or additionally separates at least two pixelsin order to reduce optical crosstalk whilst surrounding combinations ofpixels in accordance with the structure in which the infill 106 isutilised.

The light emitting pixels 116 have a light emitting surfacecorresponding to the plan view area of the pixels 116. Whilst the pixelsare shown to be square in plan view, in further examples, alternativelyor additionally the pixel plan view shapes are different. For example,the pixels 116 may assume a hexagonal shape light emitting surfaces. Infurther examples, the pixels 116 may be grouped

In an example, advantageously, the array of micro LEDs 104 a, 104 b, 104c is processed in order to provide the clear resin 112, colourconversion layers 108, 110 and the further protective layer 114 using aminimum number of processing steps. For example, such processinginvolves depositing the protective layer 114 simultaneously on eachlight emitting pixel structure. Whilst the formation of the infill 106is implemented once the array has been provided, in further examples theinfill 106 is formed at any appropriate stage of the formation of thearray of light emitting pixels.

Beneficially, the infill 106 is formed from a photo definable material.The photo definable material comprises a medium in which organicsemiconductors, are dispersed. The organic semiconductors are configuredto absorb light at a first predefined wavelength. In further examples,the organic semiconductor is also configured to absorb light of a secondpredefined wavelength different to the first predefined wavelength. Infurther examples, additionally or alternatively, the medium in which theorganic semiconductors are dispersed is definable using differentmethods, for example using thermally curing in order to harden themedium once it has been formed in around the light emitting pixels in anarray of light emitting pixels.

An absorption spectrum 200 of a photo definable material comprising aorganic semiconductor, such as that used as infill 106 in respect ofFIGS. 1A and 1B, is shown at FIG. 2 . At FIG. 2 there is shown anabsorption spectrum 200 of a photo definable material comprising organicsemiconductors dispersed in the photodefinable material. The level ofabsorption is shown on the y-axis 204 and plotted as a function ofwavelength, which is shown on the x-axis 202.

There is shown a first absorption peak 206 at 350 nm. This absorptionpeak 206 corresponds to absorption of ultraviolet light by thephotodefinable material medium in which the organic semiconductors aredispersed. Absorption of light at 350 nm enables the medium in which theorganic semiconductors are dispersed to be cured as part ofphotolithographic patterning techniques. There is also shown a secondabsorption peak 208 that extends as a range of predefined wavelengthsgreater than 420 nm. The organic semiconductors are tuned such thatsecond absorption peak 208 absorbs visible light generated by the lightemitting pixels 116.

Advantageously, the combination of organic semiconductors with theabsorption properties shown at FIG. 2 and the medium in which theorganic semiconductors are dispersed, provides an elegant and efficientmaterial to provide the infill 106 described with respect to FIGS. 1Aand 1B.

In particular, the medium in which the organic semiconductors aredispersed is arranged to cure in response to absorption of ultravioletlight, for example light at 350 nm. Therefore, ultra violet (UV) lightis used in order to harden the material in which the organicsemiconductors are dispersed. However, the medium itself is notresponsive to light of other wavelengths.

Advantageously, this facilitates fabrication steps used with mainstreamsemiconductor equipment. For example, where standard lithographicaltools are used in order to cure resins or polymers, the absorption peak206 at 350 nm shown at FIG. 2 means that UV exposures in thephotographical tools are fully absorbed and hence control of theprocesses is improved.

Further absorption at visible wavelengths as described with respect tothe second absorption peak 208 of FIG. 2 , means that the photodefinable material comprising the medium and organic semiconductors issuitable for defining separate pixels in a micro LED array of pixels.Advantageously, using organic semiconductors which can absorb in thevisible spectrum means that the requirements for processing the mediumand the functionality of the infill as an absorption layer arede-convolved.

The use of such organic semiconductors to absorb visible light isdemonstrated at FIG. 3 . FIG. 3 shows light emission spectrum 300through different thicknesses of photo-definable material comprisingorganic semiconductors configured to absorb blue light. The intensity oflight emitted from a blue LED is measured on the vertical axis 304 andwavelength is measured on the horizontal axis 302. As can be seen atFIG. 34 , the intensity peak 306 for a bare blue LED is considerablyhigher than that of a bare blue LED with one layer of organicsemiconductor 308, which is in turn greater than that of two organicsemiconductor layers 310 which is in turn greater than three organicsemiconductor layers 312. In the example of FIG. 3 , each of the organicsemiconductor layers is approximately 200 nm thick. Therefore, it can beseen that the high absorption of visible light is achieved withrelatively thin layers of material. In further examples, differentthicknesses of organic semiconductor layers are used to absorb lightemission from light emitting pixels, thereby to reduce opticalcrosstalk, e.g., by varying the functionality and/or density of theorganic semiconductors dispersed in the medium and/or using multiple,different, organic semiconductors in dispersed in the medium to reducecrosstalk.

Accordingly, crosstalk between separate light emitting pixels isachievable using even very thin layers of photo-definable materialcomprising the medium and organic semiconductor. Beneficially, suchmaterial is processable on a small scale.

Whilst the micro LED 104 a, 104 b, 104 c are blue emitting micro LEDs.In further examples, alternatively, or additionally, different microLEDs are used with different primary peak wavelengths of emission.

Advantageously, the use of organic semiconductors dispersed in a mediumin both the infill 106 and the colour conversion layers 108, 110 enablesclosely packed pixels, where pixels are separated by a distance of lessthan or equal to 2 μm and preferably less than or equal to 1 μm, to beprovided in a high resolution micro LED array with reduced opticalcrosstalk between pixels.

1. An array comprising a plurality of light emitting pixels, wherein atleast two of the plurality of light emitting pixels are separated byorganic semiconductors dispersed in a medium, wherein the organicsemiconductors are configured to absorb light of a predefinedwavelength, thereby to reduce optical crosstalk across the mediumbetween the at least two of the plurality of light emitting pixels. 2.The array according to claim 1, wherein the at least two of theplurality of light emitting pixels are separated by a distance of lessthan or equal to 2 □m and preferably less than or equal to 1 μm.
 3. Thearray according to claim 1, wherein the at least two of the plurality oflight emitting pixels each comprise a micro light emitting diode device.4. The array according to claim 3, wherein at least one of the pluralityof light emitting pixels comprise a light conversion layer arranged toreceive input light with a primary peak wavelength and convert the inputlight to output light with a different primary peak wavelength.
 5. Thearray according to claim 4, wherein the light conversion layer comprisesorganic semiconductors configured to convert the input light to outputlight.
 6. The array according to claim 1, wherein the organicsemiconductors are conjugated organic semiconductors comprising aplurality of conjugated structures, preferably wherein the organicsemiconductors are organic semiconductors, more preferably wherein theplurality of conjugated structures comprise a core and an arm.
 7. Thearray according to claim 6 wherein at least two of the plurality ofconjugated structures have a different functional property.
 8. The arrayaccording to claim 1, comprising further organic semiconductorsconfigured to absorb light of a further predefined wavelength differentto the predefined wavelength.
 9. The array according to claim 1, whereinthe organic semiconductors are configured to absorb light of apredefined range of wavelengths comprising the predefined wavelength.10. The array according to claim 1, wherein the medium is at least oneof a resin and a polymer medium.
 11. The array according to claim 1,wherein the array is a high resolution micro LED array with a pixelpitch less than 10 μm, preferably less than 4 μm.
 12. The arrayaccording to claim 1, wherein the plurality of light emitting pixelseach have a light emitting surface that is less than or equal to 100μm², preferably less than 16 μm².
 13. A method of forming an arraycomprising a plurality of light emitting pixels, wherein at least two ofthe plurality of light emitting pixels are separated by organicsemiconductors dispersed in a medium, wherein the organic semiconductorsare configured to absorb light of a predefined wavelength, thereby toreduce optical crosstalk across the medium between the at least two ofthe plurality of light emitting pixels.
 14. The method according toclaim 13, wherein the at least two of the plurality of light emittingpixels are separated by a distance of less than or equal to 2 μm andpreferably less than or equal to 1 μm.
 15. The method according to claim13, wherein the at least two of the plurality of light emitting pixelseach comprise a micro light emitting diode device.
 16. The methodaccording to claim 13, wherein at least one of the plurality of lightemitting pixels comprise a light conversion layer arranged to receiveinput light with a primary peak wavelength and convert the input lightto output light with a different primary peak wavelength.
 17. The methodaccording to claim 16, wherein the light conversion layer comprisesorganic semiconductors configured to convert the input light to outputlight.
 18. The method according to claim 13, wherein the organicsemiconductors are conjugated organic semiconductors comprising aplurality of conjugated structures, preferably wherein the organicsemiconductors are organic semiconductors, more preferably wherein theplurality of conjugated structures comprise a core and an arm.
 19. Themethod according to claim 18, wherein at least two of the plurality ofconjugated structures have a different functional property.
 20. Themethod according to claim 13, wherein the array comprises furtherorganic semiconductors dispersed in the medium, wherein the furtherorganic semiconductors are configured to absorb light of a furtherpredefined wavelength different to the predefined wavelength.
 21. Themethod according to claim 13, wherein the organic semiconductors areconfigured to absorb light of a predefined range of wavelengthscomprising the predefined wavelength.
 22. The method according to claim13, wherein the medium is at least one of a resin and a polymer medium.23. The method according to claim 13, wherein the array is a highresolution micro LED array with a pixel pitch less than 10 μm,preferably less than 4 μm.
 24. The method according to claim 13, whereinthe plurality of light emitting pixels each have a light emittingsurface that is less than or equal to 100 μm², preferably less than 16μm².